Add git cli to the docker-image, so vendir can pull get repos

Fixes #15

Signed-off-by: Pete Wall <pete.wall@grafana.com>

Dockerfile

@@ -1,7 +1,7 @@
 FROM ubuntu:24.04
 
 # perl is needed for shasum
-RUN apt-get -y update && apt-get install -y wget perl ca-certificates && update-ca-certificates && rm -rf /var/lib/apt/lists/*
+RUN apt-get -y update && apt-get install -y git wget perl ca-certificates && update-ca-certificates && rm -rf /var/lib/apt/lists/*
 
 RUN bash -c "set -eo pipefail; wget -O- https://carvel.dev/install.sh | bash"